Are we fans of fanless power supplies?

AUTHORS:Onie T. , and Lucas N.
Published:

We got our hands on the Cooler Master X Silent Edge Platinum 850, the first 850W fanless power supply in the industry. While most users might not see a huge benefit—since many power supplies already operate fanless at lower loads—it’s intriguing to see how this one handles heat without a fan.

The short answer? It holds on to a lot of it. 

Power Supply - Fan = Fanless Power Supply

Fanless power supplies are just like regular ones, minus the fan. Normally, power supplies rely on a fan to move air across heat sinks, dissipating heat from the components. Without a fan, fanless power supplies depend on natural convection and whatever airflow exists inside the computer case to stay cool.

Fanless power supplies aren’t a new concept, they’ve typically been lower wattage to keep heat levels manageable. Most power supplies, such as those used for phones, laptops, and other small devices, are designed to be fanless. However, due to the substantial power consumption and the significant heat generated by computers, fans are typically integrated into computer power supplies to ensure proper cooling.

Testing Process

We compared two power supplies: the NZXT C850 ATX 3.1 and the Cooler Master X Silent Edge Platinum 850. Both are 850W, ATX 3.1, and in the same ATX form factor. We tested them at 115V because it’s less efficient, generating more heat. We ran them both at full load (850W) for 90 minutes, then let them cool for an hour. Throughout the test, we used thermocouple probes to measure temperatures at various points on each unit.

Both power supplies were placed on metal grating inside an environmental chamber, though we didn’t use the chamber’s controls. For those unfamiliar with environmental chambers, the nature of our environmental chamber is that it generates quite a bit of air movement inside the chamber while it is running. Fanless power supplies can gain some cooling advantages from heat transfer to the case and the airflow generated by other components, however, the effectiveness of this depends on the specific system. To keep things consistent, we used a basic configuration for our tests. 

We measured temperatures in several locations:

  • Ambient: Ambient temperature within the environmental chamber.

  • Underside: Underneath the power supply, against the metal grating.

  • 12V-2x6 Connector: Pressed into the 12V-2x6 connector. 

  • Connection Panel: Affixed to the connector panel of the power supply.

  • Side Panel: Affixed to the ‘side’ of the power supply. 

  • Rear Panel: Affixed to the ‘rear’ of the power supply.

  • Behind PSU: 1 cm from the rear panel (power plug side) of the power supply.

  • Above PSU: 2 cm above the power supply. 

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It’s getting hot in here…

How does the X Silent Edge Platinum 850 actually work? It seems to rely on its own mass to absorb heat slowly. It’s almost a kilogram heavier than the NZXT, so it takes more energy to heat up. You can see this in the thermal graphs below — the NZXT heats up much faster and reaches thermal equilibrium in about 30 minutes, while the Cooler Master looks to just be approaching it after 90 minutes. 

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The Cooler Master also uses passive cooling through its design. This power supply is marketed to feature ‘composite heat pipe technology’ that draws heat away from the electronics, and that the pipes are coated with various copper textures to enhance heat dissipation. Cooler Master advertised that they have incorporated aluminum thermal molds and designed the PSU’s physical shroud with heat dissipation in mind, including multifaceted holes on top and aluminum extrusion on the sides.

The air above the Cooler Master is hotter due to natural convection, while the NZXT’s fan pulls in air and exhausts it, pushing the heat away. When the NZXT is turned off, the air above it heats up as the fan stops and heat rises naturally. 

However, there are some limitations. Cooler Master specifies that this PSU needs to be mounted with the cooling grate facing up, and there can’t be anything directly above it. This orientation helps with airflow and perhaps maximizes contact with the metal computer case, which may conduct some heat away. As expected, the sides and underside of the PSU got the hottest.

In terms of efficiency, the X Silent Edge Platinum 850 is a bit underwhelming at lower loads, although it excels at high wattages. This is likely an intentional design by Cooler Master as a slight efficiency gain at high wattages will save many more watts of power than the same gain at low wattages. The Cooler Master (represented by the blue line in our wasted energy graph) generates much less heat than the NZXT (the red line) at higher wattages. 

During testing, the X Silent Edge Platinum 850 didn’t quite hit the required efficiency at 20% load, yet it performed exceptionally well at higher loads, reaching 94% efficiency at 230V under full load. This surpasses the platinum standard and meets the titanium standard. For a full analysis of the X Silent Edge Platinum 850 along with more graphs, please visit the product page

So are we fans of fanless power supplies? 

It depends. Fanless power supplies have their pros and cons, and it really comes down to the specific user and use case. The Cooler Master X Silent Edge Platinum 850 is a solid first attempt at a high-wattage fanless PSU. Whether this represents the future of power supply design or just a cool experiment remains to be seen. Launched at a promotional price of $399 USD, with the regular MSRP at $549 USD, it is and will be more expensive than other Platinum-rated power supplies, nevertheless relatively competitive as it is an unique design with expensive components. If you want a quiet build and efficient power for demanding components, a fanless PSU could be an option.